JP2018024985A - Pile performance evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a pile performance evaluation method capable of simply evaluating performance of a pile.SOLUTION: A pile performance evaluation method includes acquisition processing S10, estimation processing S12, and evaluation processing S14. The acquisition processing S10 acquires a real displacement of a real pile head at a predetermined frequency on the basis of measured microtremors of the pile head. The estimation processing S12 estimates an estimation displacement of the pile head at the predetermined frequency on the basis of measured various elements of the ground. The evaluation processing S14 evaluates performance of a pile having the pile head on the basis of the real displacement and the estimation displacement. The estimation processing S12 includes creation processing of creating a pile/ground spring model by inputting temporary pile various elements and ground spring various elements set on the basis of the microtremors to a previously set pile/ground spring model.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pile performance evaluation method.

  Many methods have been proposed to evaluate the performance of existing piles. A typical IT test (Integrity Test) is a method in which an elastic wave is generated by hitting a pile head with a hammer and the vibration response is measured by a sensor pressed against the pile head. Although this is a simple method, only the pile length can be evaluated.

  In addition, for example, pile quality control that evaluates the soundness of a pile based on the natural frequency calculated by forcibly vibrating a pile embedded in the ground using a vibrator (or a vibrator) Methods have been proposed (Patent Documents 1 and 2 and Non-Patent Document 1). Although it is a method that can estimate the bearing capacity performance of piles, it was necessary to prepare a relatively large vibrator.

JP-A-10-153497 JP 2011-220003 A

Hidetoshi Nishioka and three others, "Proposal of non-destructive investigation method of horizontal ground resistance of pile using vibrator", Geotechnical Society, 61-8 (667), 14-17, 2013-08-01

  An object of this invention is to propose the performance evaluation method of a pile which can evaluate the performance of a pile easily.

[Application Example 1]
The performance evaluation method for piles according to this application example is
An acquisition process for acquiring an actual displacement at a predetermined frequency of the actual pile head based on the measured fine movement of the pile head;
An estimation process for estimating an estimated displacement at a predetermined frequency of the pile head based on the measured ground specifications;
An evaluation process for evaluating the performance of the pile having the pile head based on the actual displacement and the estimated displacement;
It is characterized by including.

  According to the pile performance evaluation method according to this application example, it is possible to easily evaluate the performance of the pile by measuring the fine movement of the pile head and the specifications of the ground.

[Application Example 2]
In the performance evaluation method for piles according to this application example,
The continuous fine movement in the acquisition process is the first continuous fine movement,
The estimation process includes
A measurement process for measuring the specifications of the ground based on the second constant tremor in the ground;
A calculation process for calculating a ground displacement at a predetermined frequency based on the specifications of the ground;
Creating a first pile / ground spring model by inputting the temporary pile specifications and the ground spring specifications set based on the second constant fine movement into a preset pile / ground spring model Processing, and
The estimated displacement can be estimated by inputting the ground displacement to the created first pile / ground spring model.

  According to the performance evaluation method of a pile according to this application example, the estimated displacement of the pile head can be estimated from the ground displacement by setting the pile / ground spring model in advance.

[Application Example 3]
In the performance evaluation method for piles according to this application example,
The estimation process includes
When there is a difference as a result of comparing the actual displacement and the estimated displacement,
A correction process for creating a second pile / ground spring model by changing pile specifications in the first pile / ground spring model so that a difference between the actual displacement and the estimated displacement is within a predetermined range;
The estimated displacement can be corrected using the created second pile / ground spring model, and the evaluation process can be performed using the corrected estimated displacement.

  According to the performance evaluation method for a pile according to this application example, the pile specifications in the first pile / ground spring model are changed so that the difference between the actual displacement and the estimated displacement is within a predetermined range. By obtaining the spring model, it is possible to grasp and evaluate the performance closer to the actual pile.

[Application Example 4]
In the performance evaluation method for piles according to this application example,
The second microtremor is measured by microtremor array exploration;
The calculation processing calculates the ground displacement at least the depth of the pile length of the pile based on the measurement result of the microtremor array exploration,
The estimated displacement is a value using at least one of a horizontal-rotational displacement ratio (u / θ) and a horizontal-vertical displacement ratio (u / v) of the pile head in the first pile / ground spring model. Yes,
The first microtremor is measured by a first micrometer installed on the pile head,
The actual displacement is at least one of a horizontal-rotational displacement ratio (u / θ) and a horizontal-vertical displacement ratio (u / v) of the pile head calculated based on the measurement result of the first micrometer. It can be a value using one.

  According to the pile performance evaluation method according to this application example, since the ground displacement can be calculated based on the microtremor array exploration, the ground displacement can be calculated without drilling or excavating the ground. Moreover, since each displacement of a pile head can be calculated based on a 1st microtremor meter, the loading apparatus and vibration apparatus of a pile are unnecessary, and it can calculate by a nondestructive inspection. Furthermore, since each displacement of a pile head can be calculated based on a 1st microtremor meter, there is no restriction | limiting in the length of a pile which can be measured.

FIG. 1 is a diagram schematically showing a pile and the ground. FIG. 2 is a flowchart of a pile performance evaluation method. FIG. 3 is a cross-sectional view showing an installation state of the first continuous fine movement measuring apparatus and the second continuous fine movement measuring apparatus. FIG. 4 is a plan view of a pile head on which the first continuous fine movement measuring device is installed. FIG. 5 is a schematic diagram for explaining the actual displacement of the pile head. FIG. 6 is a flowchart for explaining the estimation process. FIG. 7 is a schematic diagram for explaining a pile / ground spring model. FIG. 8 is a plan view for explaining the second continuous fine movement measuring apparatus. FIG. 9 is a graph showing the horizontal displacement of the ground at a predetermined frequency. FIG. 10 is a graph showing a pile head response (u / θ) at a predetermined frequency.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are essential constituent requirements of the present invention.

  The performance evaluation method for a pile according to the present embodiment is based on an acquisition process for obtaining an actual displacement at a predetermined frequency of the actual pile head based on the measured fine movement of the pile head, and on the measured ground specifications. An estimation process for estimating an estimated displacement of the pile head at a predetermined frequency, and an evaluation process for evaluating the performance of the pile having the pile head based on the actual displacement and the estimated displacement. To do.

1. Relationship between pile and ground The relationship between the pile 10 and the ground 22 will be described with reference to FIG. FIG. 1 is a diagram schematically showing the pile 10 and the ground 22.

  As shown in FIG. 1, the pile 10 is in the ground 22 and the pile head 12 appears on the ground surface 20. The pile head 12 may be in the ground 22.

  The pile head 12 is the top of the pile 10. The pile 10 is a columnar structural member for transmitting the load of the structure to the ground 22 via a foundation or the like. Examples of the pile 10 include material piles such as a wooden pile, a precast concrete pile, a reinforced concrete pile, and a steel (tube) pile. Moreover, as the pile 10, there exist types, such as a driving pile, a cast-in-place pile, an embedding pile, from a construction surface, for example. Furthermore, as a pile, from the functional aspect, for example, a support pile that supports the upper structure mainly by the tip (bottom end) support force, and a friction pile that mainly supports the upper structure by the frictional force between the circumferential surface of the pile and the ground There are such types.

  Although the ground 22 is always slight, it vibrates constantly, and such a small ground vibration is always called a fine movement. Microtremors are minute ground vibrations that propagate through the ground 22, for example, artificial vibrations such as vibrations generated by vehicles traveling on the ground and vibrations generated from factory machinery, and natural vibrations caused by wind and waves. Caused by mechanical vibrations.

  The fine movement of the ground 22 is transmitted to the pile 10 integrated with the ground 22 to vibrate the pile head 12. On the other hand, the formation of the ground 22 can be estimated using a known measurement method. Therefore, the present inventors estimated the displacement of the pile head 12 due to microtremors using the measured specifications of the ground 22 and compared it with the actually measured displacement of the pile head 12 to determine the performance of the pile 10. The idea was to evaluate

2. Pile Performance Evaluation Method The pile 10 performance evaluation method will be described with reference to FIG. FIG. 2 is a flowchart of the performance evaluation method of the pile 10.

As shown in FIG. 2, the performance evaluation method of the pile 10 includes an acquisition process (S10) and an estimation process (S1).
2) and an evaluation process (S14). The order of the acquisition process (S10) and the estimation process (S12) may be reversed.

  The acquisition process (S10) acquires the actual displacement of the actual pile head 12 at a predetermined frequency based on the measured constant fine movement of the pile head 12 (hereinafter referred to as “first constant fine movement”). A specific example of the first constant fine movement measuring method will be described later.

  Here, the displacement is the amount of change in the position of the pile head 12, but is not limited thereto, and may be a value that can be compared based on the amount of change.

  The estimation process (S12) estimates an estimated displacement of the pile head 12 at a predetermined frequency based on the measured specifications of the ground 22. A specific example of the estimation process (S12) will be described later.

  Here, the specifications of the ground 22 are elements related to the ground 22 that are necessary for estimating the estimated displacement of the pile head 12 at a predetermined frequency using the dynamic model of the pile 10 in the estimation process (S12). 10 layer thicknesses from the depth of the support layer 24 to about twice the depth, the density of the ground 22 (mass per unit volume), shear wave velocity and shear wave damping constant, density wave velocity and density wave There is an attenuation constant. Which element is used as the specifications of the ground 22 is appropriately selected according to the method used for the estimation process (S12). As the specifications of the ground 22, various known ground survey methods can be used. Examples of ground survey methods include microtremor array exploration, surface wave exploration, velocity logging (PS logging), elastic wave exploration, magnetic exploration, electrical exploration (specific resistance two-dimensional exploration), subsurface radar exploration, gravity exploration, The estimation from the standard penetration test (N value) result can be used. In this embodiment, a measurement method using microtremor array exploration will be described later.

  The evaluation process (S14) evaluates the performance of the pile 10 having the pile head 12 based on the actual displacement and the estimated displacement.

  Here, the performance of the pile 10 is the state of the pile 10 obtained by the estimation process (S12). The state of the pile 10 is estimated and estimated from, for example, the specifications of the pile 10 (temporary pile specifications) and the temporary pile specifications assumed in the estimation process (S12). The provisional pile specifications are elements related to the pile 10 necessary for setting a mechanical model of the pile 10 described later. For example, the density of the pile 10, the cross-sectional area of the pile 10, the Young's modulus of the pile 10, the pile 10 There are a secondary moment, a pile diameter, a pile length (depth from the ground surface 20), and the like. Which element is used as the pile specification is appropriately selected according to the method used for the estimation process (S12).

  Here, the performance evaluation of the pile 10 is, for example, an evaluation whether the performance of the pile 10 is as designed (same as the provisional pile specifications), and how much the performance of the pile 10 whose design value is unknown ( There is an evaluation that it is approximate to the provisional pile specifications.

  Thus, according to the performance evaluation method of the pile 10, the performance evaluation of the pile 10 can be easily performed by measuring the specifications of the ground 22 and the first constant fine movement of the pile head 12.

2-1. Acquisition Process The acquisition process (S10) will be described with reference to FIGS. FIG. 3 is a cross-sectional view showing an installation state of the first continuous fine movement measuring device 30 and the second continuous fine movement measuring device 40, and FIG. 4 is a plan view of the pile head 12 on which the first continuous fine movement measuring device 30 is installed. FIG. 5 is a schematic diagram for explaining the actual displacement U of the pile head 12.

An acquisition process (S10) acquires the actual displacement in the predetermined frequency of the actual pile head 12 based on the 1st constant fine movement of the pile head 12 measured. The measuring method of the first constant fine movement of the pile head 12 is not particularly limited as long as the actual displacement of the pile head 12 at the predetermined frequency can be measured. The first continuous fine movement can be measured by, for example, a first fine movement meter 32 installed on the pile head 12. Since each displacement of the pile head 12 can be calculated based on the first micrometer 32, a loading device and a vibration device for the pile 10 are unnecessary and can be calculated by nondestructive inspection. Moreover, since each displacement of the pile head 12 can be calculated based on the 1st microtremor meter 32, there is no restriction | limiting in the length of the pile 10 which can be measured like an IT test.

  As shown in FIG. 3 and FIG. 4, the first constant tremor measuring device 30 is predetermined from a plurality of first tremor meters 32 installed on the surface of the pile head 12 and measured values measured by the first tremor meter 32. And a control unit 34 that calculates an actual displacement at a frequency. Control unit 34 includes a recording unit (not shown), a power storage unit, and a calculation unit. The recording unit records the measurement value of the first microtremor meter 32, the power storage unit supplies electric power necessary to operate the first microtremor meter 32, and the calculation unit calculates the pile head 12 from the measurement value of the first microtremor meter 32. The actual displacement of is calculated.

  As shown in FIG. 3, the first microtremor meter 32 can be installed at three locations corresponding to the apex of the equilateral triangle. The number of first microtremor meters 32 is not particularly limited as long as it is a number necessary for measuring the target actual displacement. In addition to the horizontal displacement and the vertical displacement, the inclination of the pile head 12 is determined. When measuring, 3 or 5 is preferable. The first micrometer 32 is preferably capable of measuring two horizontal components and one vertical component of the pile head 12. When the first microtremor meter 32 can measure two horizontal components, one vertical component, and the inclination of the pile head 12, only one may be used.

  The first fine meter 32 may be any device that can measure minute vibrations. For example, a known fine meter such as an acceleration sensor or a velocity sensor can be used.

  The predetermined frequency in the first constant fine movement of the pile head 12 is a plurality of predetermined frequencies. The displacement of the pile head 12 is determined according to the frequency. Since the predetermined frequency in the second fine movement described later also corresponds to the first constant fine movement, it includes at least the same frequency as the predetermined frequency in the first constant fine movement.

  As shown in FIG. 5, the pile head 12 indicated by the broken line is moved by the actual displacement U (indicated by the arrow) to the pile head 12 indicated by the solid line by the vibration of the ground 22 (for example, the second constant fine movement 56). The actual displacement U of the pile head 12 can be expressed by a horizontal displacement u, a vertical displacement v, and an inclination θ in the pile head 12. The calculation unit in the control unit 34 calculates the actual displacement of the pile head 12, for example, the horizontal-rotational displacement ratio (u / θ) and horizontal− A value using at least one of the vertical displacement ratios (u / v) can be calculated.

  Thus, since each displacement of the pile head 12 can be calculated based on the 1st microtremor meter 32, the loading apparatus and vibration apparatus of the pile 10 are unnecessary, and can be calculated by a nondestructive inspection. Furthermore, since each displacement of the pile head 12 can be calculated based on the first micrometer 32, the measurable length of the pile 10 is not limited.

2-2. Estimation Process The estimation process (S12) will be described with reference to FIGS. 2, 3, and 6 to 10. 6 is a flowchart for explaining the estimation process (S12), FIG. 7 is a schematic diagram for explaining the pile / ground spring model 50, and FIG. 8 is a plan view for explaining the second constant tremor measuring device 40. FIG. 9 is a graph showing the horizontal displacement of the ground 22 at a predetermined frequency, and FIG. 10 is a graph showing the pile head response (u / θ) at the predetermined frequency.

The estimation process (S12) estimates an estimated displacement of the pile head 12 at a predetermined frequency based on the measured specifications of the ground 22. The estimation process (S12) can employ various methods that can estimate the estimated displacement of the pile head 12.

  It is considered that how much the pile head 12 is displaced by vibration at a predetermined frequency has a specific value determined from the specifications of the ground 22 and the specifications of the pile 10. This is because the vibration of the ground 22, for example, the depth distribution of the ground displacement at the time of the second constant tremor is determined from the specifications of the ground 22, and how the displacement of the ground 22 is transmitted to the pile 10 is determined by the specifications of the pile 10. .

  As shown in FIG. 6, the estimation process includes, for example, a measurement process (S120) that measures the specifications of the ground 22 based on the second constant fine movement in the ground 22, and a ground having a predetermined frequency based on the specifications of the ground 22. The calculation process (S121) for calculating the displacement, and the preliminary pile specifications and the ground spring specifications set based on the second constant fine movement are input to the preset pile / ground spring model. And a creation process (S122) for creating a 1 pile / ground spring model, and the estimated displacement can be estimated by inputting the ground displacement to the created first pile / ground spring model.

  Thus, the estimated displacement of the pile head 12 can be calculated from the ground displacement by setting the first pile / ground spring model in advance. Details of each process will be described later.

  In addition, as shown in FIG. 6, in the estimation process, when there is a difference as a result of comparing the estimated displacement and the actual displacement, the difference between the estimated displacement and the actual displacement falls within a predetermined range. It also includes a correction process (S128) for creating the second pile / ground spring model by changing the pile specifications in the ground spring model, and correcting the estimated displacement using the created second pile / ground spring model. Evaluation processing can be performed using the later estimated displacement.

  In this way, by obtaining the second pile / ground spring model by changing the pile specifications in the first pile / ground spring model so that the difference between the estimated displacement and the actual displacement falls within the predetermined range, It is possible to grasp and evaluate near performance. Details of the correction process (S128) will be described later.

2-2-1. Measurement Process The measurement process (S120) measures the specifications of the ground 22 based on the second constant fine movement in the ground 22. The method of measuring the specifications of the ground 22 based on the second constant fine movement of the ground 22 in the measurement process (S120) is a method capable of measuring the specifications of the ground 22 necessary to calculate the ground displacement at a predetermined frequency of the ground 22. If it is, it will not be limited to microtremor.

  The second permanent tremor can be measured by microtremor array exploration. Since the ground displacement can be calculated based on the microtremor array exploration, the ground displacement can be calculated without drilling or excavating the ground 22.

  A method of measuring the second constant tremor of the ground 22 by microtremor array exploration will be described with reference to FIGS. 3 and 8.

  As shown in FIG. 3 and FIG. 8, in the microtremor array exploration, microtremors at multiple points are simultaneously observed by a plurality of second tremorometers 42 on the ground surface 20, and the phase velocity of the obtained surface wave is inversely analyzed. This is a ground investigation method for estimating the S wave structure of the ground 22. The second microtremor meter 42 can be a seismometer capable of measuring minute vibrations. The second fine meter 42 may be an acceleration sensor.

  The arrangement of the second fine meter 42 can be, for example, the apex of an equilateral triangle on the ground surface 20. The second microtremor meter 42 may be arranged at the vertices of a plurality of equilateral triangles. The second micrometer 42 is arranged around the pile 10 in order to obtain the specifications of the ground 22 around the pile 10.

  The stratum structure of the ground 22 can be identified by microtremor array exploration. If the stratum structure of the ground 22 can be identified, the ground displacement in the vibration of a predetermined frequency can be estimated.

2-2-2. Calculation Process The calculation process (S121) calculates the ground displacement at a predetermined frequency based on the specifications of the ground 22. The method for calculating the ground displacement in the calculation process (S121) is not particularly limited. The calculation process (S121) can calculate the ground displacement of at least the depth of the pile 10 based on the measurement result of the microtremor array exploration, for example. This is because the ground displacement that greatly affects the displacement of the pile 10 is included if at least the ground displacement at the depth of the pile length can be calculated.

  In general, ground displacement in microtremor is “normal mode solution” (Yoshiaki Hisada “Efficient calculation method of normal mode solution and green function in stratified ground”, Architectural Institute of Japan, No.501, pp.49-56. , 1997). The “normal mode solution” represents the vibration response of the ground considering only the contribution of surface waves. The “normal mode solution” can be calculated by elastic wave theory if the formation of the ground 22 is known.

  FIG. 9 is a part of the “normal mode solution” calculated based on the stratum structure of the ground 22 identified by the microtremor array exploration. Here, as a “normal mode solution” at frequencies of 5 Hz, 10 Hz, 20 Hz, and 40 Hz, the depth distribution of the displacement in the horizontal direction of the ground 22 is shown in a graph. The frequency shown here is a part of the predetermined frequency. Thus, the ground displacement at each frequency can be calculated using the “normal mode solution”.

  If the ground displacement is calculated based on the microtremor array exploration, the ground 22 need not be bored or excavated. In addition, as long as the specifications of the ground 22 necessary for calculating the ground displacement at a predetermined frequency can be obtained, other measurement methods can be employed in addition to the microtremor array exploration.

  The ground displacement is a change amount of the position of the ground 22 around the pile 10.

2-2-3. Creation process The creation process (S122) inputs the temporary pile specifications and the ground spring specifications set based on the second constant fine movement into the previously set pile / ground spring model and inputs the first pile.・ Create a ground spring model. The estimated displacement can be estimated by inputting the ground displacement to the first pile / ground spring model created in this way. Thus, the presumed displacement of the pile head can be estimated from the ground displacement by setting the pile / ground spring model in advance.

FIG. 7 is a schematic diagram illustrating the pile / ground spring model 50. The pile / ground spring model 50 is a dynamic model of the pile 10 (FIG. 3 etc.). Specifically, the pile / ground spring model 50 models the pile 10 into a single pile (beam) 52, and a ground spring 54 is attached along the pile 52 to represent a mechanical effect due to the presence of the surrounding ground 22. Model. Pile-ground spring model 50 is, for example, knowing the displacement of the ground and (u _g, etc.) and ground spring constant and the pile (temporary) specifications, it is possible to obtain the displacement in the pile head 53 (u, etc.).

The ground spring 54 is a mechanical element for quantitatively representing the interaction between the pile 52 and the ground spring model 50, which is caused by the difference in rigidity between the pile 52 and the ground 22. A plurality of ground springs 54 are arranged in the depth direction z of the pile 52 so as to operate independently, and a spring constant corresponding to the rigidity of the ground 22 can be set for each ground spring 54. By the displacement of the ground 22 at a depth of each ground spring 54 (u _g, etc.), each ground spring stress can be calculated applied to corresponding parts of the pile 52 in 54, or pile 52 by the stress degree deformation Can be calculated.

Pile-ground spring model 50, for example, the following formula (1) and (2), the displacement of the ground 22 for each ground spring 54 _(u g, _{v g)} by inputting, in the longitudinal direction of the pile 52 The resulting displacement (u, v) can be determined virtually.

Here, [rho: the density of the pile 52, A: cross sectional area of the pile 52, t: time, E: Young's modulus of the pile 52, I: section secondary moment of the pile 52, z: depth, _{k h:} horizontal subgrade reaction force factor, B: pile diameter, u: horizontal displacement of the pile 52, _{u g:} horizontal displacement of the ground 22, _{k v:} vertical ground reaction force coefficient, v: vertical displacement of the pile, _{v g:} a vertical displacement of the ground 22 is there.

  The physical meaning of each term in the formulas (1) and (2) is as follows.

First item on the left side: Inertial force term of the pile 52, Second item on the left side: Restoring force term on the pile 52, Third item on the left side: Ground reaction force term against displacement of the pile 52, Right side: External force term on the pile 52 (Force due to ground displacement).

Vertical displacement v _g of the horizontal displacement u _g and ground 22 of the ground 22 is estimated from the specifications of the ground 22, and horizontal subgrade reaction coefficient of ground spring 54 k _h and vertical ground reaction force coefficient k _{v (spring} constant) If the temporary specifications of the pile 52 are determined, the displacement u of the pile head 53 can be calculated by solving the differential equations of the equations (1) and (2). Formulas (1) and (2) are examples, and other known formulas may be used as described above. The temporary specifications of the pile 52 are, for example, elements related to the pile necessary for setting the dynamic model of the pile. For example, the density of the pile, the cross-sectional area of the pile, the Young's modulus of the pile, the secondary moment of inertia of the pile, There are pile diameter, pile length (depth from the ground surface) and so on. The temporary specifications of the pile 52 can be obtained from design information when the actual pile 10 is constructed. If there is no design information at the time of construction, an appropriate provisional specification of the pile 52 may be estimated, but a correction process described later is required.

As the pile / ground spring model 50, a known model can be used. For example, there is a model used by a response displacement method in a seismic calculation method. Many methods for determining the horizontal ground reaction force coefficient k _h and the vertical ground reaction force coefficient k _v (spring constant) of the ground spring 54 have been proposed. In the present embodiment, the initial value is sequentially corrected in the process of “correction processing” to be described later. Therefore, the initial value may be determined by any method. For example, a typical ground spring setting method is described in the formula of k _h : Francis (Francis, AJ “Analysis of Pile Groups with Flexural Resistance”, J. Am.
Soil Mech. and Foundations Div. , ASCE, Vol. 90, no. Sm3, pp. _1-32,1994), k v: formula (Randolf of Randolf (Randolph), M. F. and Wroth, "Analysis of Deformation of Vertically Loaded Piles" of C. P., J Geotech Engrg Div, .... ASC
E, Vol. 104, pp. 1465-1488, 1978), a method using a Mindlin solution (Mindlin, RD "Force at a Point in the Interior of a Semi-Infinite Solid", J. Appl. Phys., 7). , Pp. 195-202, 1936), thin-layer method (Masayuki Hasegawa, Shoichi Nakai, “Study on group pile efficiency based on impedance function of pile foundation”, Architectural Institute of Japan, No. 417, pp. 133-145, 1990), Architectural Institute of Japan Basic Structural Design Guidelines ("Architecture Basic Design Guidelines", Architectural Basic Structural Design Guidelines, pp. 173-313, 2001), and other organizations (national land) The methods presented by the Ministry of Transport, Japan Society of Civil Engineers, Railway Research Institute, Japan Road Association, etc. That.

Next, the first pile-ground spring model created in the creation process (S122), ground displacement at a predetermined frequency _{(u g, v} g) to input estimates the estimated displacement of the pile head 53 (S124).

  Next, a comparison process (S126) for comparing the estimated displacement and the actual displacement at a predetermined frequency of the pile head 12 acquired by the acquisition process (S10) described above is executed. If it is determined in the comparison process (S126) that the estimated displacement and the actual displacement are substantially the same (YES), the estimation process ends. When it is determined in the comparison process (S126) that the estimated displacement and the actual displacement are not substantially the same (NO), a correction process (S128) is executed.

2-2-4. Correction Process The correction process (S128) is performed when it is determined in the comparison process (S126) that the estimated displacement and the actual displacement are not substantially the same, for example, when there is a difference between the estimated displacement and the actual displacement. ,Run. The correction process (S128) creates the second pile / ground spring model by changing the pile specifications in the first pile / ground spring model so that the difference between the estimated displacement and the actual displacement falls within a predetermined range. The correction process (S128) can be repeatedly executed until the estimated displacement and the actual displacement are substantially the same.

  Thus, the actual pile is obtained by changing the pile specifications in the first pile / ground spring model and obtaining the second pile / ground spring model so that the difference between the estimated displacement and the actual displacement is within a predetermined range. A performance closer to 10 can be grasped and evaluated.

  The estimated displacement in the comparison process (S126) is at least one of a horizontal-rotational displacement ratio (u / θ) and a horizontal-vertical displacement ratio (u / v) of the pile head 53 in the first pile / ground spring model. It can be the value used.

  The actual displacement in the comparison process (S126) is calculated based on the measurement result of the first microtremor meter 32 (FIG. 4), and the horizontal-rotational displacement ratio (u / θ) and horizontal-vertical displacement ratio (pile head 12). It can be a value using at least one of u / v).

  FIG. 10 is an example showing the actual displacement 60, the estimated displacement 62, and the reference displacements 64 and 66, with the horizontal axis representing the frequency (Hz) and the vertical axis representing the pile head response (u / θ). The estimated displacement 62 indicates the horizontal-rotational displacement ratio (u / θ) of the estimated displacement of the pile head 53 obtained from the design value, and the actual displacement 60 is the actual displacement of the actual pile head 12 calculated from the value of the first microtremor meter 32. The horizontal-rotational displacement ratio (u / θ) is shown. The actual displacement 60 is an actual measurement value at a plurality of predetermined frequencies set appropriately by each circle. Reference displacement 64 is an estimated displacement (u / θ) of the pile head 53 when it is assumed that the tip of the pile 52 has not reached the support layer in the ground 22, and the estimated displacement 62 is a depth of 10 m at the pile 52. This is the estimated displacement (u / θ) of the pile head 53 when it is assumed that it is broken at the center of the pile 52.

It can be seen that the actual displacement 60 is closer to the estimated displacement 62 than the reference displacements 64 and 66. The estimation process (S12) may be terminated assuming that the estimated displacement 62 is substantially the same as the actual displacement 60, and the pile specifications that have been temporarily set may be modified to approximate the estimated displacement 62 to the actual displacement 60. . Here, the estimation process (S12) is terminated assuming that they are substantially the same, and the evaluation process (S14) is executed. In the evaluation process (S14), the estimated displacement of the pile head 53 after correction in the second pile / ground spring model corrected in the correction process (S128) is used.

  Although only the horizontal-rotational displacement ratio (u / θ) is compared in FIG. 10, the comparison may be made using both the horizontal-vertical displacement ratio (u / v).

  In this way, by comparing using the displacement ratio, it is possible to obtain a stable result by eliminating the environmental variation factors.

  The values of the estimated displacement and the actual displacement in the correction process (S128) are not limited to the horizontal-rotational displacement ratio (u / θ) and the horizontal-vertical displacement ratio (u / v), but are values relating to the displacement of the pile heads 12, 53. Other values may be used as long as they are present.

2-3. Evaluation Process As shown in FIG. 2, the evaluation process (S14) is executed using the result of the estimation process (S12). If the evaluation process (S14) is the same as the temporary pile specifications (design time) set in the creation process (S122) or the correction process (S128) of the estimation process (S12), for example, the pile 10 as designed. It can be evaluated that there is. Moreover, if the evaluation process (S14) approximates the performance of the pile 10 whose design value is unknown to the temporary pile specifications corrected by the correction process (S128), the specification of the actual pile 10 is estimated. It is possible to perform the performance evaluation of the pile 10.

  In the example shown in FIG. 10, the pile 10 is substantially the same as the specifications of the pile with the design value, and it can be determined that the pile 10 as designed is being constructed.

  Thus, according to the performance evaluation method of the pile 10 which concerns on this embodiment, the performance evaluation of the pile 10 can be performed easily.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Pile, 12 ... Pile head, 20 ... Ground surface, 22 ... Ground, 24 ... Support layer, 30 ... 1st microtremor measuring device, 32 ... 1st microtremor meter, 34 ... Control part, 40 ... 2nd microtremor Measuring device 42 ... 2nd tremor meter 50 ... Pile / ground spring model 52 ... Pile 53 ... Pile head 54 ... Ground spring 56 ... 2nd fine tremor 60 ... Actual displacement 62 ... Estimated displacement 64 ... reference displacement, 66 ... reference displacement

Claims (4)

An acquisition process for acquiring an actual displacement at a predetermined frequency of the actual pile head based on the measured fine movement of the pile head;
An estimation process for estimating an estimated displacement at a predetermined frequency of the pile head based on the measured ground specifications;
An evaluation process for evaluating the performance of the pile having the pile head based on the actual displacement and the estimated displacement;
A method for evaluating the performance of a pile, comprising: In claim 1,
The continuous fine movement in the acquisition process is the first continuous fine movement,
The estimation process includes
A measurement process for measuring the specifications of the ground based on the second constant tremor in the ground;
A calculation process for calculating a ground displacement at a predetermined frequency based on the specifications of the ground;
Creating a first pile / ground spring model by inputting the temporary pile specifications and the ground spring specifications set based on the second constant fine movement into a preset pile / ground spring model Processing, and
A method for evaluating the performance of a pile, wherein the estimated displacement is estimated by inputting the ground displacement to the created first pile / ground spring model. In claim 2,
The estimation process includes
When there is a difference as a result of comparing the actual displacement and the estimated displacement,
A correction process for creating a second pile / ground spring model by changing pile specifications in the first pile / ground spring model so that a difference between the actual displacement and the estimated displacement is within a predetermined range;
The pile performance evaluation method, wherein the estimated displacement is corrected using the created second pile / ground spring model, and the evaluation process is performed using the corrected estimated displacement. In claim 2 or 3,
The second microtremor is measured by microtremor array exploration;
The calculation processing calculates the ground displacement at least the depth of the pile length of the pile based on the measurement result of the microtremor array exploration,
The estimated displacement is a value using at least one of a horizontal-rotational displacement ratio (u / θ) and a horizontal-vertical displacement ratio (u / v) of the pile head in the first pile / ground spring model. Yes,
The first microtremor is measured by a first micrometer installed on the pile head,
The actual displacement is at least one of a horizontal-rotational displacement ratio (u / θ) and a horizontal-vertical displacement ratio (u / v) of the pile head calculated based on the measurement result of the first micrometer. A method for evaluating the performance of a pile, characterized in that the value is a value using two.